Furnace-grate.



No. 795,083. PATENTBD JULY 18, 1905.

P. J. WEI'ZEL.

' FURNACE GRATE.

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PATENTED JULY 18, 1905.

I. J. WBTZBL. FURNAGE GRATE.

nrmonxon FILED JULY 16,1904.

3 SHEETS-SHEET 3.

ATTORNEY NITED STATES Patented July 18, 1905.

FRANK J. VVETZEL, OF TRENTON, NET/V JERSEY.

FURNACE-GRATE.

SPECIFICATION forming part of Letters Patent No. 795,083, dated July 18, 1905.

Application filed July 16, 1904. Serial No. 216,767.

To (.I/[Z whom, it Tll/(bjj concern.-

Be it known that I, FRANK J. VVETZEL, a citizen of the United States, residing at Trenton, in the county of Mercer and State of New Jersey, have invented certain new and useful Improvements in Furnace-Grates, of which the following is a specification.

My improvement relates especially to those furnace-grates which are known as mechanical stokers, and its object is to produce a simple and durable apparatus which will secure a more perfect and uniform combustion of fuel than has heretofore been attained, and a consequent economy and cleanliness in operation, and maintain a more even heat in the furnace, and therefore a greater and more uniform steam-pressure.

In the accompanying drawings, forming a part of this specification, Figure 1 is a rear perspective View of a stoker embodying my improvements and showing a considerable number of the main grate-bars removed, thus affording a view of the portion of the operating mechanism beneath the grate bars. Fig. 2 is a front perspective view of the stoker; and Fig. 3 is a side elevation of the stoker, the lower grate and certain accessories being indicated in section.

The furnace is constructed with a fire-bridge 1 and an arch 2, above which is placed the boiler 3. Between the front of the furnace and the fire-bridge are placed three grates, the first of which, 4, is the coking-grate, the

second, 5, is the main grate, and the third, 6,

is the dumping-grate. The main grate is composed of two series of grate-bars, one of which is stationary and the other movable or vibratory, the stationary bars 7 being placed alternately with the vibrating bars 8. The main grate-bars are supported by the side frames 9 and 10, on which are directly mounted the rock-shafts 11 and 12, these rock-shafts being journaled on the tops of said frames 9 and 10, as shown in Figs. 1 and 3. Said rock-shafts 11 and 12 have, respectively, the parallel shafts 13and 1 1 attached to the rockshafts by the posts 15, and on these parallel shafts 13 and 14 the grate-bars 8 are directly supported. The shafts 13 and 14 are connected by the link-bars l6 placed at each end of said shafts, (only one thereof being shown in the drawings,) and the said grate-bars 8 are retained in their proper positions upon said shafts 13 and 14 by said link-bars 16 and hooks 17 and 18, formed on the under side of each of said bars 8. From the lower side of the rock-shaft 12 extends a lever 19, which is connected by the link-bar 20 to the block 21. This block 21 is pivoted on the plate 22, which is firmly fixed upon the front plate of the furnace. The block 21 is of a triangular shape in general outline and has formed in one corner thereof a slot 23, in which plays the stud 24, fixed on a projecting part of the sleeve 25. This sleeve 25 is adjustably fixed upon the bar 26, which is strapped to the eccentric 27, fastened upon the shaft 28. On the shaft 28 is'also fixed the eccentric 29, to which is strapped the bar 30, which in turn is adjustably connected with the link 31, attached to the feeding mechanism 32, which feeding mechanism forms the bottom of the hopper 33. To the front of the feeding mechanism 32 is attached the rod 34, which passes in through the front of the furnace and is connected with the coking-grate 4:. (See Figs. 2 and 3.) The dumping-grate 6 is shown in its normal position in Fig. 3. Its forward edge is higher than its rear edge, and it is supported on the frames 9 and 10 by the pintle or rod 35. It is operated by the bar 36, the handle of which projects forward over the front plate of the furnace, the bar passing through said front plate and being caught thereon by a slight depression formed in the under side of the bar or in any other convenient mode. Upon freeing the bar 36 and permitting it to slide inwardly the dumping-grate drops to the position shown in the dotted lines in Fig. 3, and the cinders and ashes thereon are deposited in the ash-pit beneath the grate. The stationary bars 7 and vibratory bars 8 of the main grate 5 are provided with teeth or projections, which I shall now particularly describe. These teeth or projections, which are most clearly shown in Fig. 3, project above the tops of the grate-bars and extend down on one side thereof to a point at or near the lower edge of each grate-bar. The teeth 37,

formed on the upper part of these gratebars, have their axes at an oblique angle with the axis of the grate-bar and form a series of steps lying almost in a horizontal position with intervening spaces through which the air may pass from beneath the grate into and through the mass of fuel lying thereon., The teeth 38, formed on the lower portion of these grate-bars, have their axes nearly at right angles with the axis of the grate-bars and are formed with intervening spaces through which the air may pass to and through the fuel on the grate. The outer faces of these teeth 37 and 38 lie close to the plane face of the adjacent grate-bar. The reason for so forming and locating these teeth 37 and 38 will be hereinafter given.

On the upper part of the inner faces of the front plates of the furnace are attached tiles 39, which are formed with side grooves, so that when placed in juxtaposition the vertical openings 40 are formed between the tiles. In the side of the furnace and above the tiles 39 I form an opening or openings 41 to admit of the entrance of fresh air above the tiles 39. This outside air passes into What I call a hotair chamber, formed above the tiles by the top plate 42, placed there to inclose the same, and the heat of the furnace heats the air in this chamber to a high degree before it enters the main furnace through the openings 40.

I have not illustrated the means for rotating the shaft 28, which operates the mechanism. This shaft may be rotated by gearing or by pulley or by a small engine and the rotation duly timed.

The operation of my mechanism is as follows: Coalbeing deposited in thehopper 33 and the shaft 28 being slowly rotated, thefeeding device 32 is projected and retracted into and from the bottom of the hopper and gradually feeds the coal onto the coking-grate 4, which is slowly agitated by means of the bar 34. At the same time the rock-shafts 11 and 12 being slowly vibrated, the alternate grate-bars 8 move from the position indicated in full lines to the position indicated by dotted lines in Fig. 3 and back again to the position indicated by full lines, the movement of these grate-bars 8 being upwardly and backward and downwardly and forward. thus gradually moved from the hopper 33 down over the surfaces of the coking-grate and the main grate until it reaches and covers the dumping-grate, reaching to the front of the fire-bridge 1. As the fuel passes upon the coking-grate and becomes ignited it receives an abundant quantity'of air through the air-spaces in the coking-grate and the channels 40, formed throughthe tiles 39. The smoke generated in the coking process is thus quickly and practically entirely consumed, adding to the heat of the furnace and obviating its escape through the stack. Through the agitation of the coking and main grates The fuel isthe fuel is gradually passed down upon the main grate, Where it continues to receive a quantity of air duly proportioned to the state of its combustion. By the time the fuel reaches the lower portion of the main grate 5, where the bars are provided with the teeth 38, it is effectually coked, and live fuel is in little or no danger of falling through the interstices between the teeth 38 into the ashpit and being wasted. The teeth or projections on the coking-grate and the teeth or projections 37 on the bars of the main grate are, as has been described, formed in a series of steps, so that while the fuel is being coked it is impossible for any of it to fall into the ash-pit and be lost. Inmy construction thus described I have obviated serious objections to prior mechanisms of this kind. By providing the largest proportion of air-space in the coking-grate and less and varying proportions of. air-space in the main grate and a still smaller proportion of such space in the dumping-grate and inclining the three grates downwardly throughout their entire surfaces I can keep all the grates covered with fuel or residuum practically constantly without manual intervention, thus preventing objectionable updrafts of air through uncovered portions of any of the grates, while the amount of air admitted to the burning fuel from beneath is duly proportioned to the state of its combustion. Heretofore the air -spaces in the dumping-grate have been made as large as that in the main grate, and the upper surface of the dumping-grate has been inclined only in part if at all. As a result of such construction there is a powerful updraft of air through the dumping-grate immediately after it has been cleared by dropping it, which updraft carries up over the fire-bridge ashes and small particles of fuel which pass down upon the dumping-grate from the main grate, and the dumping-grate is thus kept bare until a sufficient mass of fuel accumulates on the main grate to topple over, fall upon, and cover the dumping-grate. This process usually occupies from one-half to three-quarters of an hour, and during that period of time the air which should be supplied to the fuel of the coking and main grates seeks the easier passage through the uncovered dumping-grate, thereby greatly reducing the heat in the furnace and causing a corresponding diminution of steam-pressure. In the prior structures this difficulty can be obviated only by manual intervention to throw down promptly upon the cleared dumping-grate fuel from the main grate, and any neglect of such precaution results seriously. By my constriction of the air-passages of the dumping-grate and the inclination of that grate throughout its entire surface I prevent the fuel and ashes delivered from the main grate being dislodged by the updraft and have produced an apparatus which automatically recovers the dumpinggrate in from one to two minutes entirely without manual intervention, thus maintaining an even and adequate combustion of the fuel on the several grates at all times with a consequent equable maintenance of steampressure heretofore quite unattainable by purely automatic stoking.

I prefer to proportion the air-openings in the several grates to the respective superficial areas thereof as follows: In the coking-grate, eighty per cent; in the upper portion of the main grate, sixty-five per cent; in the lower portion of the main grate, fifty per cent, and in the clumping-grate forty per cent. I thus afford to the burning fuel in its progress over the grate-surface such an amount of oxygen as consumes with rapidity the volatile portions of the fuel and more slowly the less volatile parts thereof, but all with equal thoroughness and also reduce the updraft through the dumping-grate with the results above mentioned.

Having thus described my invention, I claim A coking-grate, a main grate and a dumping-grate severally inclined throughout their respective surfaces, the proportions of space for admission of air to the superficial grate area being largest in the coking-grate, less in the main grate and least in the dumping-grate, the main grate comprising a series of stationary bars and a series of movable bars, the bars of one series being alternately arranged with respect to those of the other, in combination with a stationary frame supporting the main grate, rock-shafts mounted on said frame and supporting said movable bars, and means for operating said rock-shafts and the grate bars supported thereby, substantially as shown and described.

FRANK J. W ETZEL.

Witnesses:

FRANCIS (J. LOWTI-IORP, EDWIN N. TrIoRN; 

